Re: [RFC PATCH] loop: set queue logical block size

[Ming Lei <minlei@redhat.com>]

On Thu, Apr 06, 2017 at 01:19:45AM -0700, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> The request queue created when we create a loop device has the default
> logical block size of 512. When we associate the device with an fd, we
> set the block size on the block_device but don't update the logical
> block size of the request_queue. This makes it impossibe to use direct
> I/O with a backing file on a device with a block size >512, as the
> following check in __loop_update_dio() fails:
> 
> 	sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
> 	if (queue_logical_block_size(lo->lo_queue) >= sb_bsize &&
> 	    ...
> 
> Fix it by updating the logical block size when we set the fd.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  drivers/block/loop.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index cc981f34e017..1bb22903ad1a 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -941,6 +941,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
>  	/* let user-space know about the new size */
>  	kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
>  
> +	blk_queue_logical_block_size(lo->lo_queue, lo_blocksize);
>  	set_blocksize(bdev, lo_blocksize);
>  
>  	lo->lo_state = Lo_bound;

Looks fine!

Reviewed-by: Ming Lei <minlei@redhat.com>

Thanks,
Ming